Effects Of Different Ventilation Modes On Respiratory Function During General Anesthesia In Patients Undergoing Laparoscopic Colorectal Cancer Surgery

Objective T_o evaluate the effects of different ventilation modes on respiratory function during general anesthesia in patients undergoing laparoscopic colorectal cancer surgery.Methods Sixty patients aged between 18 and 60 years with BMI 18²5kg/m2 and ASA physical status I^III were randomized to receive either pressure controlled ventilation（Group P,n=30）or volume controlled ventilation（Group V,n=30）during the laparoscopic colorectal cancer surgery.T_racheal intubation was performed after anesthesia induction and then all patients received mechanical ventilation.In group P,the tidal volume（VT_）was set at 8ml/kg by adjusting the inspiratory pressure;In group V,the VT was set at 8ml/kg immediately.Respiration rate（RR）were adjusted to maintain an end-tidal CO₂ pressure（PET_CO₂）of 30⁴0mm Hg,and the rest methods of anesthesia were the same.Respiratory function,respiratory mechanics and hemodynamic variables were measured at the time of before anesthesia induction（T₀）,post-tracheal intubation 10 minutes（T₁）,post-T_rendelenburg and pneumoperitoneum 10 minutes（T₂）、 60minutes（T₃）and 120 minutes（T₄）,post-pneumoperitoneum removed and recovery in the supine position 20 minutes（T₅）.Results 1.T_here were no significant differences between the two groups in patient characteristics（P>0.05）.2.T_he Pa CO₂ was incresed in both groups at T₂、T₃、T₄、T₅ compared with T₁（P < 0.05）;But between the two groups,the Pa CO₂ was decreased at T₂、T₃、T₄、T₅ in group P compared with the group V（P < 0.05）.T_he OI and Pa O₂ were decreased,the A-a DO₂ and RI were increased in both groups at T₂、T₃、T₄ compared with T₁（P < 0.05）;But between the two groups,the OI and Pa O₂ were incresed,A-a DO₂ and RI were decreased in group P at T₂、T₃、T₄ compared with the group V（P < 0.05）.3.T_he Ppeak and Pmean were incresed,the Cdyn was decreased in both groups at T₂、T₃、T₄ compared with T₁（P < 0.05）;But between the two groups,the Ppeak was decreased,the Pmean and Cdyn were increased in group P at T₂、T₃、T₄ compared with the group V（P < 0.05）.T_he RR was increased in group V at T₃、T₄ compared with T₁（P < 0.05）,T_here was no significant difference in RR in group P at each time point（P > 0.05）;But between the two groups,the RR was decreased in group P at T₃、T₄ compared with the group V（P < 0.05）.4.T_he MAP were increased in two groups at T₂、T₃ and T₄ compared with T₀（P < 0.05）.T_here was no significant difference in MAP and HR in group P at each time point compared with group V（P > 0.05）.Conclusion Compared with volume controlled ventilation,pressure controlled ventilation can improve ventilation function,promote gas exchange,decrease airway resistance and has no significant effect on hemodynamics in patients having laparoscopic colorectal cancer surgery.